Ultraviolet stabilized petroleum hydrocarbons



United States Patent 3,518,196 ULTRAVIOLET STABILIZED PETROLEUM HYDROCARBONS Jackson S. Boyer, Claym'ont, Del., and Richard D. Cassar,

West Chester, Pa., assignors to Sun Oil Company, Philadelphia, Pa., a corporation of New Jersey No Drawing. Filed Dec. 18, 1967, Ser. No. 691,153 Int. Cl. Cm 1/24, 1/26 US. Cl. 252-56 26 Claims ABSTRACT OF THE DISCLOSURE CROSS REFERENCE TO RELATED APPLICATIONS The present application is related to our copending application Ser. No. 691,199 which relates to elastomeric compositions containing certain polymethylated muconic acids and their hydrocarbyl esters and also to our copending application Ser. No. 691,129 which relates to alpha-olefin polymeric compositions containing certain polymethylated muconic acids and their hydrocarbyl es ters, both of which are filed of even date herewith.

BACKGROUND OF THE INVENTION The present invention relates to petroleum fractions having improved ultraviolet stability. More particularly, this invention relates to petroleum fractions including petroleum distillate fuels, petroleum wax, and petroleum oil composition containing a novel ultraviolet stability improving additive.

It is well known that refined products recovered from petroleum crude oil frequently undergo deteriorative changes in use or storage, particularly when they are exposed to ultraviolet light. One explanation given for this phenomena is that refined petroleum fractions, particularly refined oils and waxes contain components which are extremely susceptible to oxidation, especially when in the presence of oxygen or ozone and ultraviolet light. Although there is disagreement with respect to the exact mechanisms involved in these changes, there is some general agreement that this ultraviolet degradation is generally the result of oxidative changes in the petroleum fraction involved.

Oxidation of petroleum oils and waxes and distillate fuels such as gasoline is known to result in the formation of organic acids as well as polymerizable products, both of which are undesirable impurities in the petroleum composition. The presence of these impurities in the petroleum compositions often is evident in the form of discoloration of the product or precipitation of solids generally referred to as sludge. Any appreciable formation of these various degradation products can affect the properties of the petroleum hydrocarbon composition in question with the result that it may become functionally unusable or commercially undesirable because of these changes.

A variety of improved refining techniques are presently employed by petroleum refiners in an attempt to reduce these undesirable characteristics. These techniques include solvent extraction, acid washing, and hydrogenation of the petroleum hydrocarbon. However, the advantages achieved by improved refining techniques often still fall short of providing a suitably unltraviolet stable product.

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Thus in many instances ultraviolet stability improving antioxidant additives are required to provide refined petroleum hydrocarbon compositions with the necessary ultraviolet stability to render those compositions commercially usable.

DESCRIPTION OF THE INVENTION It has now been discovered that certain di-, tri-, and tetramethylmuconic acids hereafter referred to as polymethylated muconic acids and their esters, when blended with certain petroleum hydrocarbon fractions, provide petroleum hydrocarbon compositions having improved resistance to ultraviolet initiated degradation.

It has been discovered that the cis-cis, cis-trans, or trans-trans isomers of a,a-dimethylmuconic acid, a,fl'-dimethylmuconic acid, u,a', 8-trimethylmuconic acid, a,fl,,8- trimethylmuconic acid, u,a,fi, 3-tetramethylmuconic acid, or their monoesters wherein one carboxyl group is attached to a C -C hydrocarbyl radical, or their diesters wherein each carbox l group is attached to a C -C hydrocarbyl radical, and mixtures thereof when added to petroleum hydrocarbons in the quantity of 0.01l0.0 weight percent based on the weight of the whole composition provides a petroleum hydrocarbon composition having improved resistance to ultraviolet degradation. The preferred concentration of polymethylated muconic acid or its esters in the petroleum hydrocarbon composition is generally in the range of 0.52.0 Weight percent.

Each of the above-disclosed polymethylated muconic acids in the cis-cis, cis-trans, or trans-trans isomeric form or mixtures thereof is effective for use in the compositions of the present invention. Also, the C -C hydrocarbyl monoesters or diesters of these acids or mixtures thereof are effective for use in the compositions of the present invention.

The C C hydrocarbyl esters included in the present invention are selected from the hydrocarbyl radicals of C -C hydrocarbons having acyclic, cyclic, and aromatic structures such as those disclosed in the text Handbook of Hydrocarbons, S. W. Ferris, Academic Press Inc., New York, N.Y. (1955), pages 249, all of which are incorporated herein by reference. The preferred esters of the present invention are the C -C hydrocarbyl monoand diesters of the polymethylated muconic acids disclosed above. Examples of the C C hydrocarbyl groups include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl cyclopentyl, methyl cyclopentyl, dicyclopentyl, cyclohexyl, phenyl, tolyl, xylyl, naphthyl, tetrahydronaphthyl, decahydronaphthyl, as well as the various isomers of each.

The diester of the muconic acid can be a mixed ester. An illustrative example is the cis-cis isomer of a,a'-dimethylmuconic acid which can be illustrated by the following structural formula:

wherein R is different from R That is to say, R can be a hydrocarbyl group of C C and R can be a different hydrocarbyl group of C C e.g., R equals cyclohexyl (C and R equals eicosyl (C Examples of some of the esters of the polymethylated muconic acids suitable for use in the compositions of the present invention include the cis-cis, cis-trans, and transtrans isomers of the monoand di-methyl esters of 11,18- dimethylmuconic acid; the monoand di-phenyl esters of a,a, 3,,B-tetramethylmuconic acid; the monoand dinaphthyl esters of a,}3,;8'-trimethylmuconic acid; the monoand di-5,6-diethylacenaphthtyl esters of a,a'-

dimethylmuconic acid; the monoand di-cyclohexyl ester of a,u-dimethylmuconic acid; the monoand di- 1,2-dimethylcycloheptyl esters of a,B'-dimethylmuconic acid; the monoand di-decahydronaphthyl esters of a,a,B,;8-tetramethylmuconic acid; the monoand dil,3-dipropylbenzyl esters of a,a'-dimethylmuconic acid; the monoand di-2,9-dimethyl-4,7-diisobutyldecyl esters of a,a',B-trimethylmuconic acid; and the monoand dianthracyl esters of u,fl'-dimethylmuconic acid; monoand di-2,6,l-trimethyl dodecyl esters of a,a,fl,p"-tetramethylmuconic acid; and the nonyl ethyl esters of a,rx',f3-trimethylmuconic acid.

Specifically it has been discovered that the cis-cis, cistrans, or trans-trans isomers of the following compounds are effective ultraviolet stability improvement additives when incorporated in certain petroleum hydrocarbon compositions. These additive compounds are selected from (a) Polymethylated muconic acids selected from the group consisting of a,a'-dimethylmuconic acid, -oc,B'-dlmethylmuconic acid, a,a,fl-trimethylmuconic acid, a,fl,,3' trimethylmuconic acid, and a,a,,8,;8'-tetramethylmuconic acid,

(b) The hydrocarbyl monoesters of said diacids wherein the hydrocarbyl group contains 1-20 carbon atoms,

(c) Hydrocarbyl diesters of said diacids wherein each hydrocarbyl contains 1-20 carbon atoms, and

(d) Mixtures of any of the above.

As noted above, polymethylated muconic acids can exist in three isomeric forms, viz. cis-cis, trans-trans, and cis-trans. As an example, the unsaturated diacid, 04, 01- dimethylmuconic acid, can be depicted by the following structural formulas:

H3O H C=C CO OH cis-cis HO O C C=C H CH;

HO O C /H C=C CH2 trans-trans H3O /C=C H C O OH H30 /H t C=C\ /CH3 cisruns HO O C /C=C\ H CO OH The preparation of each of these isomeric forms of the a,a'dimethylmuconic acid has been described in the prior art by Elvidge et al., J. Chem. Soc., pages 1026-1033 (1952). These authors show that oxidation of p-xylenol by means of peracetic acid gave the cis-cis form of the acid. The other isomeric forms were obtained indirectly by conversion of the cis-cis form. Also dimethyl esters of each of the three isomeric forms were prepared by shaking the respective DMMA with ethereal diazomethane.

The cis-cis form of polymethylated muconic acids can also be obtained by biological oxidation of p-xylene utilizing special strains of microorganisms as disclosed in U.S. application Ser. No. 509,621, filed Nov. 24, 1965.

Procedures for recovering esters of the three isomeric forms of methylated muconic acids usable in the compositions of the present invention are also disclosed in US. application Ser. No. 561,736, filed June 30, 1966.

The refined petroleum hydrocarbon fractions included in the compositions of the present invention are petroleum distillate fuel fractions, petroleum wax fractions, and petroleum oil fractions.

The petroleum distillate fuel compositions include distillate petroleum hydrocarbon fractions boiling in the 4 range of to 500 F. and normally recovered from petroleum crude oil by simple distillation. Examples of petroleum distillate fuels include gasoline, kerosine, No. l furnace oil, No. 2 furnace oil, spirits, jet fuels, and many others well known to those skilled in the art.

The petroleum wax compositions of the present invention include waxes normally recovered from waxy petroleum crude oil by refining procedures well known in the art. These procedures are generally disclosed in Kirk and Othmer, Interscience Publishers, New York, N.Y., 1953, vol. 10, pps. 211-227. Refined petroleum waxes are generally white, yellow or brown in color and are classified as parafiinic or microcrystalline. Refined petroleum waxes normally have a melting point in the range of 200 F. and an SUS viscosity at 210 F. in the range of 35-90.

One method of detecting ultraviolet degradation in a petroleum wax is by visual observation of change in color intensity of the wax. This change is apparently the result of color bodies being formed as products of UV degradation. For example, an unstabilized white petroleum wax which is exposed to ultraviolet light for a period of time will yellow.

As a means of illustrating one mode of the present invention, the following examples are given:

EXAMPLE I A white paraflin petroleum wax characterized as melting at 127 F., having an SUS viscosity at 210 F. of 44 and a penetration at 77 F. of 33 (ASTM D1321) was exposed to ultraviolet light for 72 hours in accordance with the procedures outlined in ASTM D925-50. After exposure to ultraviolet light the wax was examined and found to be substantially yellowed indicating degradation of the wax has taken place.

EXAMPLE II A sample of the dimethyl ester of trans-trans oz,ot-dimethylmuconic acid was prepared as follows:

A solution of 150 g. (0.88 mol.) of cis-cis dimethylmuconic acid obtained by biological oxidation of p-xylene and dissolved in 1 liter of 6 N NaOH is refluxed for 24 hours, diluted with 5 volumes of distilled water, and brought to pH 3 with 12 N HCl. The solid which separates at this point is filtered off and dried; it contains about 80 percent of the trans-trans acid, with a lesser amount of the cis-trans acid and a minor amount of the cis-cis acid.

The crude product thus obtained is esterified by refluxing it (140 g.) in 1 liter of methanol containing 1 cc. of concentrated H 80 until solution occurs. Cooling the reaction mixture yields the dimethyl ester of the transtrans acid in substantially pure form (M.P. 102-104 C.).

Three samples of wax identical to that disclosed in Example I were heated to F. and homogeneously blended with 0.1, 1.0, and 2.0 weight percent respectively, based on the weight of the wax of the dimethyl ester of trans-trans, a,a'-dimethylmuconic acid, which was prepared in the manner disclosed above. The three separate wax compositions were cooled to room temperature and thereafter exposed to ultraviolet light in the identical manner as disclosed in Example I. A visual examination of each of these three wax compositions revealed no discoloration or any other signs of ultraviolet initiated degraration in any of the three wax compositions containing the muconate additive.

Thus, a comparison of the additive containing wax compositions of Example II with the unstabilized wax composition of Example I illustrates the improved ultraviolet stability of petroleum wax achieved by the methods and compositions of this invention.

The petroleum oils suitable for use in the compositions of this invention are recovered from petroleum crude oil by refining procedures well known to those skilled in the art and generally disclosed in Kirk and Othrner, vol. 10,

Interscience Publ. Co., New York, N.Y. (1953), pages 143-153. Generally these oils are characterized as having an SUS viscosity at 100 F. of at least 50, a viscositygravity constant in the range of .740.980 and boiling above 500 F. at atmospheric pressure.

Petroleum oils of the above-disclosed characteristics are normally susceptible to ultraviolet degradation which is generally recognized in the form of discoloration and/ or sludge formation, both of which are undesirable.

It has been discovered that 0.0ll0.0 weight percent and preferably 0.5-2.0 weight percent of the herein disclosed specific polymethylated muconic acids and their hydrocarbyl esters when incorporated into petroleum oils hereinabove described provides a petroleum oil composition having improved resistance to ultraviolet initiated degradation.

As a means of further illustrating the present invention the following examples are herein presented:

EXAMPLE III A solvent refined hydrotreated petroleum oil having the following characteristics:

SUS viscosity at 100 F. 100 Viscosity-gravity constant 0.872 ASTM color 0.5 Gel aromatics, wt. percent 36 was blended with 0.125 wt. percent based on the weight of the whole composition of the dimethyl ester of transtrans u,a'-dimethylmuconic acid (DMMA). This composion along with a sample of the identical oil having no additive(control) were heated to a temperature in the range of 140150 F. and maintained at that temperature for a period of 24 hours during which time both samples were exposed to ultraviolet light in accordance with procedures outlined in ASTM D925-Dll. At the end of the exposure time each sample was evaluated for sludge formation and ASTM color according to the procedures outlined in ASTM D1500. The results of these tests appear in the table under the heading of control and Example III.

EXAMPLE IV An oil composition identical to that disclosed in Example III was prepared and tested in accordance with the procedures outlined in Example III with the exception that 0.25 wt. percent of the dimethyl ester of trans-trans a,a-dimethylmuconic acid was blended with the base oil. The results of the testing of this composition appear in the table under Example IV.

EXAMPLE V An oil compositon identical to that disclosed in Example III was prepared and tested in accordance with the procedures outlined in Example III with the exception that 0.5 wt. percent of the dimethyl ester of trans-trans u,x'-dimethylmuconic acid was blended with the base oil. The results of the testing of this composition appear in the table under Example V.

EXAMPLE VI An oil composition identical to that disclosed in Example III was prepared and tested in accordance with the procedures outlined in Example III with the exception that 1.0 wt. percent of the dimethyl ester of trans-trans 11,1!- dimethylmuconic acid was blended with the base oil. The results of the testing of this composition appear in the table under Example VI.

EXAMPLE VII An oil composition identical to that disclosed in Example III was prepared and tested in accordance with the procedures outlined in Example III with the exception that 2.0 wt. percent of the dimethyl ester of trans-trans a,a-dimethylmuconic acid was blended with the base oil. The results of the testing of this composition appear in the table under Example VII.

A comparison of the results shown in table for Examples III-VII with the tested control clearly demonstrates the improved resistance to discoloration and sludge formation accomplished by the addition of small quantities of the dimethyl ester of trans-trans c d-dimethylmuconic acid.

For purposes of practicality, the amount of polymethylated muconic acids and/ or their hydrocarbon esters which can be added to petroleum oils and petroleum Waxes to achieve the improvements herein disclosed is in the range of (MOI-10.0 weight percent based on the whole composition. The preferred range is 0.05-2.0 weight percent.

The petroleum wax and petroleum oil compositions of the present invention can include those property improving additives such as polymers, antioxidants, fillers, and extenders normally used in the preparation of commercial wax and oil compositions.

Ultraviolet stability improving additives other than the dimethyl ester of trans-trans a,a'-dimethylmuconic acid set forth in the examples given above can be substituted therefore in any of the petroleum hydrocarbon fractions disclosed hereinabove and provide analogous results. Included among these additives are the cis-cis, cis-trans, and trans-trans isomers of any of the polymethylated muconic acids disclosed above as well as these isomers of the monoesters of each of these acids wherein the ester contains a C C hydrocarbyl group and also the diesters of each of these acids wherein each ester contains a C C hydrocarbyl group. Any combination of the above additives with any of the disclosed refined petroleum hydrocarbon fractions provide results analogous to those disclosed in the examples given above. Also, petroleum -waxes, oils and distillate fuels other than those disclosed in the examples stated above can be utilized in the compositions of the present invention with analogous results being obtained.

Compositions in which refined petroleum hydrocarbon fractions form a significant part, e.g., lubricating greases, wax coating compositions, etc., Which are subject to ultraviolet degradation fall within the scope of the compositions suitable to be included in the present invention.

The polymethylated muconic acids and rnuconates disclosed above can be incorporated into the refined petroleum hydrocarbon fractions disclosed above in the form of colloidal dispersions, physical mixes or as solutions where the acid or ester is sufficiently soluble in the petroleum fraction being stabilized; however, complete solubility of the polymethylated muconic acid or ester is not required to provide the desired UV stability.

We claim:

1. A refined petroleum hydrocarbon composition hav ing improved ultraviolet stability comprising a refined violet stability improving quantity of a material selected (c) hydrocarbyl diesters of said muconic acids wherein the hydrocarbyl groups each contain l-20 carbon atoms, and

(d) mixtures thereof.

2. A composition according to claim 1 wherein the polymethylated muconic acids are the cis-cis isomers.

3. A composition according to claim 1 wherein the polymethylated muconic acids are the cis-trans isomers.

4. A composition according to claim 1 wherein the polymethylated muconic acids are the trans-trans isomers.

5. A composition according to claim 1 wherein the quantity of ultraviolet stability improving material is in the range of 001-100 weight percent.

6. A composition according to claim 2 wherein the quantity of ultraviolet stability improving material is in the range of 001-100 weight percent.

7. A composition according to claim 3 wherein the quantity of ultraviolet stability improving material is in the range of 001-100 weight percent.

8. A composition according to claim 4 wherein the quantity of ultraviolet stability improving material is in the range of 001-100 weight percent.

9. A composition according to claim 1 wherein the refined petroleum hydrocarbon fraction is wax.

10. A composition according to claim 5 wherein the refined petroleum hydrocarbon fraction is wax.

11. A composition according to claim 1 wherein the refined petroleum hydrocarbon fraction is an oil.

12. A composition according to claim 5 wherein the refined petroleum hydrocarbon fraction is an oil.

13. A composition according to claim 1 wherein the ultraviolet stability improving material is the dimethyl ester of a,a'-dimethylmuconic acid.

14. A composition according to claim 4 wherein the ultraviolet stability improving material is the dimethyl ester of a,a-dimethylmuconic acid.

15. A composition according to claim 5 wherein the ultraviolet stability improving material is the dimethyl ester of u,a'-dimethylmuconic acid.

16. A composition according to claim 6 wherein the ultraviolet stability improving material is the dimethyl ester of a,a-dimethylmuconic acid.

17. A composition according to claim 10 wherein the ultraviolet stability improving material is the dimethyl ester of a,a-dirnethylmuconic acid.

18. A composition according to claim 1 wherein the refined petroleum hydrocarbon fraction is a distillate fuel.

19. A composition according to claim 5 wherein the refined petroleum hydrocarbon fraction is a distillate fuel.

20. A composition according to claim 10 wherein the ultraviolet stability improving material is the dimethyl ester of trans-trans a,a-dimethylmuconic acid.

21. A composition according to claim 12 wherein the ultraviolet stability improving material is the dimethyl ester of trans-trans a,a-dimethylmuconic acid.

22. A composition according to claim 19 wherein the ultraviolet stability improving material is the dimethyl ester of trans-trans a,a-dimethylmuconic acid.

23. A composition according to claim 1 wherein the quantity of ultraviolet stability improving material is in the range of 0.5-3.0 weight percent.

24. A composition according to claim 2 wherein the quantity of ultraviolet stability improving material is in the range of 0.5-2.0 weight percent.

25. A composition according to claim 3 wherein the quantity of ultraviolet stability improving material is in the range of 0.5-2.0 weight percent.

26. A composition according to claim 4 wherein the quantity of ultraviolet stability improving material is in the range of 0.5-2.0 weight percent.

References Cited UNITED STATES PATENTS 2,747,979 5/1956 Thompson 44-70 2,846,461 9/1958 Thompson et al. 44-70 3,383,289 5/1968 Raymond et al. -30

DANIEL E. WYMAN, Primary Examiner Y. H. SMITH, Assistant Examiner U.S. Cl. X.R.

Patent No.

UNITED STATES PATENT OFFICE Dated June 30, .1970

Inventor(s) Jackson S Boyer "Richard D. Cassar It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 6 lines 65-75 Claim 1 should appear as follows:

A refined petroleum hydrocarbon composition having improved ultraviolet stability comprising a refined petroleum hydrocarbon fraction containing an ultraviolet stability improving quantity of a material selected from the group consisting of hydrocarbyl monoesters of said muconic acids wherein the hydrocarbyl group contains 1-20 carbon atoms,

SIGIIEI) AND 95 l-HE WC 51m Anon:

mm: E. mm, .m. lmesting Oificer comiaaiomr of Patents 1 FORM PO-IOSO (10-69) USCOMM-DC 60376-P69 fl' U.S. GOVERNMENT PRINTING OFFICE 1 IQIB 0-366-334 Patent: No. 3,518, 196 Dated June 30, 1970 Inventor(s) Jackson S Boyer Richard D. Caesar It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 6 lines 65-75 Claim .1 should appear as follows:

1. A refined petroleum hydrocarbon composition having improved ultraviolet stability comprising a refined petroleum hydrocarbon fraction containing an ultraviolet stability improving quantity of a material selected from the group consisting of (a) polymethylated muconic acids selected from Cl,(1' -dimethy.lmuconic acid, (1,6 -dimethylmuconic acid, d,oL",B-trimethylmuconic acid,

d,t3,6'-trimethylmuconic acid, and 0L,d',5,[3'- tetramethylmuc onic acid,

(b) hydrocarbyl monoesters of said muconic acids wherein the hydrocarbyl group contains 1-20 carbon atoms,

DEC 51m m Am mm M. M I wmm x. m- AnestingOfficm' 810m of Patents FORM USCOMM-DC 6OS75-P69 9 U-S GOVERHHENY PRINTING OFFICE: I'll DJ-3ll 

